KR20220087349A - High-strength medium entropy alloy and manufacturing method for the same - Google Patents

Abstract

The present invention relates to a high-strength medium entropy alloy and a method for manufacturing the same, and more specifically, to an alloy containing a multi-component alloy matrix and Si and having an FCC (Face Centered Cubic)-based phase while maintaining an FCC-based single phase while maintaining an existing transition metal It has higher strength than alloys.

Description

High strength medium entropy alloy and manufacturing method thereof

The present invention relates to a high-strength medium entropy alloy and a method for manufacturing the same, and more particularly, to a lattice distortion-strengthened medium entropy alloy that maintains an FCC single phase while increasing strength and hardness, and a method for manufacturing the same.

High-entropy alloys (HEAs) are multi-element alloys obtained by alloying five or more constituent elements in similar proportions instead of major elements constituting the alloy. High entropy alloys have high mixed entropy in the alloy, so intermetallic compounds or mesophases are not formed, and single-phase structures such as face-centered cubic (FCC) or body-centered cubic (BCC) are not formed. It is a metal material with

Two important factors in designing such a high-entropy alloy are the compositional ratio of the elements constituting the alloy and the compositional entropy of the alloy system.

The first among them is the composition ratio of the high entropy alloy. A high entropy alloy must consist of at least five elements, and the composition ratio of each alloying element is defined as 5 to 35 at%. In addition, when other elements other than the main alloy constituent elements are added during the manufacture of the high entropy alloy, the amount of the addition should be 5 at% or less.

In general, alloys are classified into high-entropy alloys, medium-entropy alloys (MEAs), and low-entropy alloys (LEAs) according to the constituent entropy (Sconf) according to the composition of alloying elements.

These high-entropy and medium-entropy alloys have a very high price of alloying elements included in the alloy system currently being researched, and are a major obstacle to commercialization because heavy alloying elements are mainly used. Recently, studies on lightweight high-entropy alloys manufactured by combining lightweight alloying elements have been conducted, but intermetallic compounds are formed when alloying elements close to the same fraction according to the definition of high-entropy alloys are added due to the low solubility between the lightweight alloying elements. This limits the plastic deformation of the alloy and deteriorates the workability, which does not lead to actual commercialization.

For the industrialization of high-entropy and medium-entropy alloys, it is essential to secure price competitiveness through adjustment of alloying elements and to implement excellent mechanical properties.

It is an object of the present invention to provide a lattice distortion-strengthened medium entropy alloy that maintains a single phase FCC while increasing strength and hardness.

It is also an object of the present invention to provide a novel mid-entropy alloy that maintains a single phase FCC while increasing lattice distortion by adding Si to a known medium-entropy alloy.

It is also an object of the present invention to provide a method for manufacturing a high-strength mesoentropic alloy.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the appended claims.

The mid-entropy alloy according to the present invention for solving the above-mentioned problems is characterized in that it maintains the FCC (Face Centered Cubic)-based phase and increases the strength while increasing the lattice distortion by adding Si to the multi-component alloy matrix. do it with

More specifically, the middle entropy alloy of the present invention includes a multi-component alloy matrix and Si, and the multi-component alloy matrix includes two or more of Cr, Co, Ni, and V, and a Face Centered Cubic (FCC)-based phase including alloys having

Preferably, the midentropy alloy according to an embodiment of the present invention is represented by the following Chemical Formula 1, and may include an alloy having a Face Centered Cubic (FCC)-based single phase.

[Formula 1]

_CrCoNiSix

(It satisfies the condition of O<x≤0.4)

Also preferably, x may satisfy the condition of 0.15≤x≤0.3.

In addition, the midentropy alloy according to an embodiment of the present invention is represented by the following Chemical Formula 2, and may include an alloy having a face centered cubic (FCC)-based single phase.

[Formula 2]

CoNiSi _x

(O<x≤0.25)

In addition, the midentropy alloy according to an embodiment of the present invention is represented by the following Chemical Formula 3, and may include an alloy having a Face Centered Cubic (FCC)-based single phase.

[Formula 3]

VCoNiSi _x

(It satisfies the condition of O<x≤0.1)

Next, the method of manufacturing a mesoentropic alloy according to another embodiment of the present invention comprises the steps of: preparing a mixed powder in which an alloy matrix element and Si powder are mixed; to do; and producing an alloy by sintering the cast alloy at a high temperature, wherein the alloy matrix element includes at least two of Cr, Co, Ni and V, and the alloy is a Face Centered Cubic (FCC)-based phase has

The present invention can provide a novel mesoentropic alloy with improved mechanical properties at room temperature and high temperature.

In addition, the mid-entropy alloy according to the present invention has higher strength than the conventional transition metal alloy while maintaining the FCC-based single phase.

In addition, the medium entropy alloy manufacturing method of the present invention can maximize the strengthening effect by changing the microstructure of the medium entropy alloy by a homogenization process by high-temperature sintering.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

1 to 3 are graphs showing XRD (X-ray diffraction) measurement results of alloys according to an embodiment of the present invention.
4 is a graph showing tensile test results of alloys according to Examples 1 to 5 of the present invention.
5 to 16 are SEM photographs of an alloy according to an embodiment of the present invention.

The above-described objects, features and advantages will be described below in detail with reference to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present invention pertains will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail.

Throughout the specification, unless otherwise stated, each element may be singular or plural.

As used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “consisting of” or “comprising” should not be construed as necessarily including all of the various components or various steps described in the specification, some of which components or some steps are It should be construed that it may not include, or may further include additional components or steps.

Hereinafter, a medium entropy alloy and a method for manufacturing the same according to the present invention will be described.

mesoentropic alloy

In order to supplement the low strength characteristics of the FCC series high entropy and medium entropy alloys, the present invention provides a novel alloy having excellent mechanical properties by doping Si to the conventional alloy and controlling the doping amount.

The central entropy alloy according to the present invention includes a multi-component alloy matrix and Si, and the multi-component alloy matrix includes two or more of Cr, Co, Ni and V, and an alloy having a Face Centered Cubic (FCC)-based phase includes

The central entropy alloy of the present invention includes a multi-component alloy matrix as in the prior art, and the alloy matrix includes two or more of Cr, Co, Ni and V. And, the alloy of the present invention includes Si together with the alloy matrix. In the alloy of the present invention, Si is doped into the conventional alloy to increase lattice distortion, maintain FCC-based single phase, and increase hardness and strength.

Preferably, the alloy of the present invention may include the two or more types of alloy matrix in the same atomic ratio (at%). In addition, it is preferable that the alloy of the present invention has an FCC-based single phase.

More specifically, the midentropy alloy according to an embodiment of the present invention may include an alloy represented by the following Chemical Formula 1 and having a Face Centered Cubic (FCC)-based single phase.

[Formula 1]

_CrCoNiSix

(It satisfies the condition of O<x≤0.4)

Also preferably, x may satisfy the condition of 0.15≤x≤0.3.

In other words, Cr, Co, Ni, and Si in Formula 1 have a ratio of 1:1:1:x.

In addition, the mid-entropy alloy according to an embodiment of the present invention may include an alloy represented by the following Chemical Formula 2 and having a Face Centered Cubic (FCC)-based single phase.

[Formula 2]

CoNiSi _x

(O<x≤0.25)

In other words, Co, Ni, and Si in Formula 2 have a ratio of 1:1:x.

In addition, the mid-entropy alloy according to an embodiment of the present invention may include an alloy represented by the following Chemical Formula 3 and having a Face Centered Cubic (FCC)-based single phase.

[Formula 3]

VCoNiSi _x

(It satisfies the condition of O<x≤0.1)

In other words, V, Co, Ni and Si in Formula 3 have a ratio of 1:1:1:x.

Method for manufacturing a neutral entropy alloy

Next, the method for producing a midentropy alloy according to the present invention comprises the steps of: preparing a mixed powder in which an alloy matrix element and Si powder are mixed; heating and dissolving the mixed powder and casting to a predetermined shape; and high-temperature sintering of the cast alloy; the alloy matrix element includes at least two of Cr, Co, Ni, and V, and the alloy has a Face Centered Cubic (FCC) single phase.

First, the method for producing a neutral entropy alloy according to the present invention includes preparing a mixed powder in which an alloy matrix element having the same atomic ratio % and Si powder are mixed.

The multi-component alloy matrix includes at least two of Cr, Co, Ni and V. In addition, it is preferable that the alloy of the present invention contains the two or more types of alloy matrix in the same atomic ratio (at%), and the alloy of the present invention preferably has an FCC-based single phase. The preferred atomic % ratio of the alloy is as described above.

Next, the method for producing a mid-entropy alloy according to the present invention includes the step of heating and dissolving the mixed powder and casting it in a predetermined shape. The casting method is not particularly limited, and casting may be performed in the form of charging the raw material in the crucible.

In addition, the manufacturing method of the present invention may include the step of forming a mechanical alloying powder for mechanical alloying by milling the mixed powder before the casting step.

Next, the method for producing a medium entropy alloy according to the present invention includes the step of producing an alloy by sintering the cast alloy at a high temperature. Here, the alloy can be homogenized by high-temperature sintering.

The high-temperature sintering may be performed in a vacuum atmosphere, an inert gas atmosphere, an oxygen atmosphere, or an atmosphere containing at least one of nitrogen, boron, and carbon.

In addition, the high-temperature sintering may be performed at a temperature of 900 °C to 1300 °C for 1 to 12 hours, and more preferably at a temperature of 900 °C to 1300 °C for 6 hours or more.

The intermediate entropy alloy manufactured by the above-mentioned manufacturing method according to the present invention may include the above-described alloy.

Hereinafter, the present invention will be described in more detail through preferred embodiments of the present invention.

<Example>

1. Preparation of Examples and Comparative Examples

A mixed powder was prepared by mixing an alloy matrix element and Si powder at the same atomic ratio in the ratio shown in the table below. Each pure element was prepared in the form of pellets of 10 mm or less with a purity of 99.5% or more.

This was charged into a crucible, heated to 1550° C., and melted, and then the molten alloy was prepared as an ingot in a zirconia crucible. During the solidification process, the pressure was maintained at a level of 2.5 bar. After manufacturing the ingot, the homogenization process was all conducted at 1100° C. for 6 hours in an inert gas Ar atmosphere.

Cr(at%) Co(at%) Ni (at%) Si (at%) Comparative Example 1 33.33 33.33 33.33 0 Example 1
(Si 0.15) 31.75 31.75 31.75 4.77 Example 2
(Si 0.3) 30.30 30.30 30.30 9.09 Example 3 (Si 0.35) 29.85 29.85 29.85 10.45 Example 4 (Si 0.4) 29.41 29.41 29.41 11.76 Example 5
(Si 0.45) 28.98 28.98 28.98 13.04

Co(at%) Ni (at%) Si (at%) Example 6 47.5 47.5 5 Example 7 45 45 10 Example 8 42.5 42.5 15 Example 9 40 40 20

V(at%) Co(at%) Ni (at%) Si (at%) Example 10
(Si 0.1) 32.26 32.26 32.26 3.2 Example 11
(Si 0.2) 31.25 31.25 31.25 6.25 Example 12
(Si 0..3) 30.13 30.13 30.13 9.6

2. Test evaluation

The test results regarding the HV hardness and tensile strength of the prepared alloy are described in the table below. In addition, XRD results of the prepared alloys are shown in FIGS. 1 to 3, and tensile strength results of the prepared alloys (Examples 1 to 5) are shown in FIG. 4 . And, SEM pictures of the prepared alloy are shown in FIGS. 5 to 16 .

HV hardness YS(MPa) UTS (MPa) EI.(%) Comparative Example 1 153.0±3.0 275.0 630.0 83.8 Example 1
(Si 0.15) 194.5±5.0 311.1 759.9 76.8 Example 2
(Si 0.3) 210.4±5.0 359.9 761.1 63.8 Example 3 (Si 0.35) 225.2±11.5 359.3 799.2 69.1 Example 4
(Si 0.4) 223.8±6.9 363.3 664.4 35.0 Example 5
(Si 0.45) 301.6±21.2 514 702.7 5.7

HV hardness Example 6 127.4±1.7 Example 7 153.5±8.2 Example 8 340.6±13.5 Example 9 494.0±20.2

HV hardness Example 10
(Si 0.1) 253±4.6 Example 11
(Si 0.2) 398.4±18.1 Example 12
(Si 0..3) 656.2±30.2

First, referring to Table 4, it can be seen that Examples 1 to 5 doped with Si have both hardness and strength superior to those of the alloy not (Comparative Example). However, Example 5 doped with a Si ratio of 0.45 has a Ni2Si type IMC along with the FCC phase as shown in FIG. 1 . Accordingly, it was confirmed that Example 5 had high hardness and strength, but showed brittleness with an elongation of 5.7%.

Next, referring to Tables 5 and 6, it can be seen that all of the examples doped with Si have excellent hardness. However, referring to FIGS. 2 and 3 , Examples 8 and 9 and Examples 11 and 12 are predicted to show brittleness as they have Ni2Si type IMC in addition to the FCC phase.

As such, it can be seen that the mid-entropy alloy according to the present invention has higher strength due to doping of Si compared to the conventional alloy.

As described above, the present invention has been described based on preferred embodiments, but the present invention is not limited by the embodiments disclosed herein, and various modifications may be made by those skilled in the art within the scope of the technical spirit of the present invention. It is self-evident that it can In addition, although the effects according to the configuration of the present invention have not been explicitly described and described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

Claims (13)

Containing a multi-component alloy matrix and Si,
The multi-component alloy matrix includes at least two of Cr, Co, Ni and V,
Containing an alloy having a FCC (Face Centered Cubic)-based phase,
mesoentropic alloy.
The method of claim 1,
the alloy is
It is represented by the following formula (1)
With FCC (Face Centered Cubic) phase
mesoentropic alloy.

[Formula 1]
_CrCoNiSix
(It satisfies the condition of O<x≤0.4)
3. The method of claim 2,
where x is
It satisfies the condition of 0.15≤x≤0.3
mesoentropic alloy.
The method of claim 1,
the alloy is
It is represented by the following formula (2)
With FCC (Face Centered Cubic) phase
mesoentropic alloy.

[Formula 2]
CoNiSi _x
(O<x≤0.25 satisfies the condition)
The method of claim 1,
the alloy is
It is represented by the following formula (3)
With FCC (Face Centered Cubic) phase
mesoentropic alloy.

[Formula 3]
VCoNiSi _x
(O<x≤0.1 satisfies the condition)
preparing a mixed powder in which the alloy matrix element and Si powder are mixed;
heating and dissolving the mixed powder and casting it into a predetermined shape; and
Including; sintering the cast alloy at a high temperature to produce an alloy;
The alloy matrix element includes two or more of Cr, Co, Ni and V,
The alloy has a Face Centered Cubic (FCC)-based phase,
Method for manufacturing a mesoentropic alloy.
7. The method of claim 6,
The high-temperature sintering step comprises:
It is performed in a vacuum atmosphere, an inert gas atmosphere, an oxygen atmosphere, or an atmosphere containing at least one of nitrogen, boron, and carbon.
Method for manufacturing a mesoentropic alloy.
7. The method of claim 6,
The high-temperature sintering step comprises:
carried out for 1 to 12 hours at a temperature of 900° C. to 1300° C.
Method for manufacturing a mesoentropic alloy.
9. The method of claim 8,
The high-temperature sintering step comprises:
carried out at a temperature of 900 ° C. to 1300 ° C. for more than 6 hours
Method for manufacturing a mesoentropic alloy.
7. The method of claim 6,
the alloy is
It is represented by the following formula (1)
With FCC (Face Centered Cubic) phase
Method for manufacturing a mesoentropic alloy.

[Formula 1]
_CrCoNiSix
(It satisfies the condition of O<x≤0.4)
11. The method of claim 10,
where x is
It satisfies the condition of 0.15≤x≤0.3
Method for manufacturing a mesoentropic alloy.
7. The method of claim 6,
the alloy is
It is represented by the following formula (2)
With FCC (Face Centered Cubic) phase
Method for manufacturing a mesoentropic alloy.

[Formula 2]
CoNiSi _x
(O<x≤0.25 satisfies the condition)
7. The method of claim 6,
the alloy is
It is represented by the following formula (3)
With FCC (Face Centered Cubic) phase
Method for manufacturing a mesoentropic alloy.

[Formula 3]
VCoNiSi _x
(It satisfies the condition of O<x≤0.1)

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